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Full text of "The Cambridge Natural History"

xii                      FUSION  OF CERVICAL VERTEBRAE                   35!

developed supra-occipital in the adult. Here again the Zeuglo-
donts are more typically Mammalian, for In them the parietals

have  a   normal  development;  and   situation,  rising  even  into  a

median crest as in so many quadrupeds. The bones related
to the organ of hearing, the tjinpanlcs and petrous bones, are
very solid and dense in structure. Moreover they are but

a,

FIG. 185.' — A section of a skull of a yoting Oaa*ing Whale (&l$Mf<epna!i&s melaa). x $•. a,
Angle ; a», anterior uares ; AS, allaphenoid ; &%, basihyal ; JBO, basioccipital ; JBS,
basisphenoid ; cd, eoadyle ; cp, coronoid process ; JExO, exocclpital ; JV, frontal ;
«/, inferior dental canal ; 2JPt interparletal ; MJ5* ossified portion of the me«eth-
moid ; Sfz, maxilla ; TVo, nasal ; /*«» parietal ; Per, periotlc ; PL, palatine ; PMx*
premaxilla ; _p«, posterior iiares ; PŁt presptenoid j P/, pterygoid ; 4, syaipfeysis
of mandible ; oh, stylohyal ; SO, supra-occipital ; Sq, squamosal ; th9 tliyroliyal j
Vot vomer. (From Flower's

loosely attached to surrounding bones, and are thus easily and
frequently lost. Nearly the only mammals which reseioble the
Whales in the fact that the pterygoids sometimes meet in the
middle line below are the Edentata (Anteater and Armadillo, see
p. 16*7). But in both groups this peculiarity is not universal
The vertebral column is remarkable for the fact that more or
fewer of the cervical vertebrae may be fused together into a short
and compact mass. This is seen at Its maximum in the
j&oloena and Meolxxla^na^ The odontoid process of th»